A 46-year-old female patient presents to the Urgent Care center requesting a strep test. Her symptoms included a burning sensation in the mouth with a bad metallic taste for over two weeks. The patient had no insurance, so she waited until the symptoms were intolerable. Today, she noted white patches in her throat, so she sought care requesting a strep test. She can eat and drink, has no fever or chills, no cold symptoms, and otherwise feels well. She has a past medical history significant for asthma and uses a controller inhaler. She denies any other past medical history.
She is afebrile and has normal vital signs. She appears well and is in no distress. Consider the photograph of her throat to the left.
Which of the following is the most plausible diagnosis based on the history and physical findings?
Further history was obtained revealing the patient was recently treated for sinusitis with an antibiotic and prednisone. She uses a fluticasone inhaler daily for asthma and was unaware that she needed to rinse her mouth after use. She is also a smoker.
Answer: C. Pseudomembranous candidiasis
The findings in this patient indicate pseudomembranous candidiasis, also known as oral thrush. It is the most frequently recognized form of candidiasis. Thrush presents as white plaques on the buccal mucosa, tongue, and palate which can be scraped off revealing red patches. The exudate resembles curdled milk.
Thrush is the most common of oral fungal infections caused by a group of saprophytic fungi including 8 species of the genus Candida. Candida albicans is the most common of these and accounts for 70-80% of all oral isolates. It is a dimorphic fungus existing in both yeast and hyphal forms. Only the hyphal form is associated with oral Candida infections. About 30-50% of the population has Candida as part of their normal oral microflora. 1
Although Candida is an opportunistic pathogen, it is part of the normal human gut flora, including the mouth. In healthy patients, the yeast lives in balance with other microorganisms and does not cause infection. When this balance is altered by elements like immunosuppression, local factors, or systemic alterations, infection can occur.  (See Table 1.)
There are several other forms of oral candidiasis which include erythematous candidiasis, acute atrophic candidiasis, and chronic atrophic candidiasis. Erythematous candidiasis is usually due to medications causing dry mouth, wearing dentures for extended periods, and xerostomia. Acute atrophic candidiasis, also called antibiotic sore mouth, causes erythema of the mouth and atrophy of the tongue papilla. Patients complain of an oral burning sensation. This may also be caused by iron deficiency, Vitamin B12 deficiency, and poorly controlled diabetes mellitus (DM). Chronic atrophic candidiasis is found on the hard palate in denture wearers, especially those who do not remove their dentures overnight. It is also called denture stomatitis.
The diagnosis of oral candidiasis of any form is made based on clinical signs and symptoms. There may be no symptoms, or symptoms may include a cottony sensation in the mouth, loss or alteration of taste, or a burning sensation. The classic white patches on the buccal mucosa, palate, tongue, and oropharynx may or may not be present. In many cases, the patient is treated empirically with antifungals, and resolution of symptoms confirms the diagnosis.
If the diagnosis is in question, testing can be performed. Exfoliative cytology, biopsy, and culture can all be used to confirm the diagnosis. The easiest and fastest of these in the Urgent Care setting is exfoliative cytology. A moistened tongue blade is used to scrape the exudate along with the superficial keratinocytes and then sent to the laboratory for PAS staining. If available a KOH prep can be performed in the Urgent Care to confirm the diagnosis immediately. Biopsy and culture take significantly longer to obtain results.1
When a patient with a Candida infection is evaluated, it is necessary to determine why the infection developed. Typically, there is a condition or comorbidity that predisposes the patient to this infection. If these conditions can be modified, it aids in the treatment of the infection and may prevent recurrence.2 Patients who present with oral Candida who have no apparent risk factors should be investigated further. Diabetic patients, especially those poorly controlled or as yet diagnosed will have increased glucose in saliva, which promotes greater adherence of fungal elements to the oral mucosa. Blood glucose or HgbA1c should be evaluated if diabetes is suspected.
Although much less common after the advent of protease inhibitors for HIV, thrush is an AIDS defining illness in those who have HIV infection. Testing for HIV should be considered for initial Candida infections if no other risk factors are identified. Further testing for immune deficiency should be investigated if needed.
For patients with dentures with erythematous candidiasis, removing dentures nightly and cleaning well will mitigate some of the risk of recurrence. Medication lists should be reviewed and adjusted if any are found to cause dry mouth. Patients using steroid inhalers should be encouraged to rinse their mouths out after use. Finally, every effort should be made to prescribe antibiotics and steroids in an evidence-based manner to prevent thrush from unneeded medications.
In this case there were multiple risk factors for the development of pseudomembranous candidiasis. She used a steroid inhaler without oral rinsing, was a smoker, and recently took antibiotics and steroids. It is not surprising that she developed this infection. Although her oral hygiene appears to be poor, it is not the cause of the white lesions or the infection. Leukoplakia has a more well-defined, geographic, lacey appearance. Streptococcal pharyngitis does not cause an exudate on the buccal mucosa, palate, or tongue.
Our patient was treated with clotrimazole troches 10mg five times per day for seven days, and her symptoms resolved in four days. Other options include miconazole 50mg buccal tablet daily for seven to 14 days, nystatin 500,000 units four times daily, or in severe cases fluconazole 200mg once followed by 100-200mg daily for seven to 14 days. Providers should discuss with patients the various choices; clotrimazole has a black licorice taste that may not be palatable to some patients, nystatin has an artificial butter cream frosting taste and is a thick suspension that needs to be swished in the mouth for as long as possible. Patients may not find these options palatable or may find the multiple daily dosing difficult to follow. Topical agents are less likely to cause any systemic effects. Systemic agents such as fluconazole may be reserved for more advanced infections.